U-Net: Center-cropping Skip Connections

The problem, from first principles

U-Net (Ronneberger et al., 2015) copies high-resolution encoder features to the decoder through skip connections. Unpadded convolutions shrink the maps, so the copied features are center-cropped to match.

From theory to code

Implement center_crop(x, h, w), returning the central region of a feature map.

Constraints

• The crop is centered; with an odd difference the extra row or column goes to the bottom or right.

Hints